I have a question about Prefect (docker) Workers. We have a work pool with several workers in it. Occasionally we want to restart these workers (for example to update Prefect or to change some configuration). What is the recommended approach to do this? Ideally I'd tell the worker to stop accepting new work, but still finish whatever flows it is running. Then when it is done, it can quit and I can restart it. So far all I have found is that I can stop the entire pool. Is there a way to signal to a worker to finish existing work but stop accepting new flows?